usb连接的PTP模式，同时显示内置、外置SD卡内容

原生态的android中，PTP只支持本地存储设备，外部sd设备没有添加。但可以通过修改代码添加，前提是你必须要有android的源码,我的是在MTK平台下面开发的。

修改文件：

1:...\os\Enviroment.java

添加下面两行代码

public static String DIRECTORY_SD2_PICTURES = "Pictures2";    
public static String DIRECTORY_SD2_DCIM = "DCIM2";

2: packages\privoiders\MediaProvider\src\com\android\providers\media\MtpService.java

//add for two PTP disk. start.
  private static final String[] PTP_DIRECTORIES_SD2 = new String[] {
         Environment.DIRECTORY_SD2_DCIM,
         Environment.DIRECTORY_SD2_PICTURES,
     };
  //add for two PTP disk. end.

3.
     private void addStorageDevicesLocked() {
         /*if (mPtpMode) {
             // In PTP mode we support only primary storage
             final StorageVolume primary = StorageManager.getPrimaryVolume(mVolumes);
             final String path = primary.getPath();
             if (path != null) {
                 String state = mStorageManager.getVolumeState(path);
                 if (Environment.MEDIA_MOUNTED.equals(state)) {
                     addStorageLocked(mVolumeMap.get(path));
                 }
             }
         } else  cancelled. for PTP two disk. */{
             for (StorageVolume volume : mVolumeMap.values()) {
                 addStorageLocked(volume);
             }
         }
     }

 

4.
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
         synchronized (mBinder) {
             updateDisabledStateLocked();
    isUsbConfigured = (intent == null ? false
     :intent.getBooleanExtra(UsbManager.USB_CONFIGURED, false));

            mPtpMode = (intent == null ? false
                     : intent.getBooleanExtra(UsbManager.USB_FUNCTION_PTP, false));
             String[] subdirs = null;
             if (mPtpMode) {
                 int count = PTP_DIRECTORIES.length;
     int count2 = PTP_DIRECTORIES_SD2.length; //add. for PTP two disks.
                 subdirs = new String[count+count2]; //add. for PTP two disk.
                 for (int i = 0; i < count; i++) {
                     File file =
                             Environment.getExternalStoragePublicDirectory(PTP_DIRECTORIES[i]);
                     // make sure this directory exists
                     file.mkdirs();
                     subdirs[i] = file.getPath();
                 }
     for (int i = count; i < count+count2; i++) { //modify. for PTP two disks.
                     
     File file = new File(System.getenv("SECONDARY_STORAGE"), PTP_DIRECTORIES_SD2[i-count]);  //wqtao. modify. for PTP two disks.                    
                    // make sure this directory exists
                     file.mkdirs();
                     subdirs[i] = file.getPath();
                 }
             }

 

5.
     private void volumeMountedLocked(String path) {
         // Add for update Storage
         StorageVolume[] volumes = mStorageManager.getVolumeList();
         mVolumes = volumes;
         // Add for update Storage
         for (int i = 0; i < mVolumes.length; i++) {
             StorageVolume volume = mVolumes[i];
             if (volume.getPath().equals(path)) {
                 mVolumeMap.put(path, volume);
                 if (!mMtpDisabled) {
                     // In PTP mode we support only primary storage
                     /*if (volume.isPrimary() || !mPtpMode)   cancelled. for PTP two disk. */{
                         addStorageLocked(volume);
                     }
                 }
                 break;
             }
         }
     }

先./mk [Your ProjectName] update-api，再remake.